The invention relates to an air intake system for an internal combustion engine which improves the air charge of the individual cylinders of an engine.
In known intake systems, the length and cross-section of the individual intake pipes are configured in such a way that the respective cylinders are filled to an optimum degree at a particular engine speed by a resonance effect. Since this resonance effect disappears at different engine speeds, the only remaining possibility for achieving a supplementary charging effect is to impose the desired oscillation frequency on the air column in the intake pipes by means of an externally excited oscillation generator.
German DOS 3,729,998 discloses a cylinder charge control system in which an electromagnetically operated diaphragm is arranged in the transfer duct between the air filter box and the intake pipe. This diaphragm is controlled as a function of operating parameters in order to produce defined pressure oscillations in the intake pipe. The disadvantage in this arrangement is that the diaphragm is arranged in the transfer duct and, as a result, poses a considerable resistance to flow.
Also known, for example, from JP-A2 61-76 719, are intake systems in which a diaphragm is arranged in the outer wall of the air collecting box. But in multi-cylinder internal combustion engines such an arrangement can cause oscillations in the individual intake pipes which have negative effects on each other as it may happen in the arrangement described earlier.
The object of the invention is therefore to provide an intake system wherein predetermined acoustic pressure oscillations can be generated in the air columns in the individual intake pipes without interference between the air flows in the individual intake pipes.